Method and apparatus for sending data and control information in a wireless communication system

ABSTRACT

Techniques for sending control information in a communication system are described. In an aspect, control information may be sent in a first frequency location (e.g., a first set of subcarriers) if data is not being sent and in a second frequency location (e.g., a second set of subcarriers) if data is being sent. In another aspect, control information may be processed in accordance with a first processing scheme if data is not being sent and with a second processing scheme if data is being sent. In one design of the first scheme, a CAZAC sequence may be modulated with each modulation symbol for control information to obtain a corresponding modulated CAZAC sequence, which may be sent on the first set of subcarriers. In one design of the second scheme, modulation symbols for control information may be combined with modulation symbols for data, transformed to frequency domain, and mapped to the second set of subcarriers.

The present application claims priority to provisional U.S. ApplicationSer. No. 60/819,268, entitled “A METHOD AND APPARATUS FOR AN ACK CHANNELFOR OFDMA SYSTEM,” filed Jul. 7, 2006, assigned to the assignee hereofand incorporated herein by reference.

BACKGROUND

I. Field

The present disclosure relates generally to communication, and morespecifically to techniques for sending data and control information in awireless communication system.

II. Background

Wireless communication systems are widely deployed to provide variouscommunication services such as voice, video, packet data, messaging,broadcast, etc. These wireless systems may be multiple-access systemscapable of supporting multiple users by sharing the available systemresources. Examples of such multiple-access systems include CodeDivision Multiple Access (CDMA) systems, Time Division Multiple Access(TDMA) systems, Frequency Division Multiple Access (FDMA) systems,Orthogonal FDMA (OFDMA) systems, and Single-Carrier FDMA (SC-FDMA)systems.

In a wireless communication system, a Node B (or base station) maytransmit data to a user equipment (UE) on the downlink and/or receivedata from the UE on the uplink. The downlink (or forward link) refers tothe communication link from the Node B to the UE, and the uplink (orreverse link) refers to the communication link from the UE to the NodeB. The Node B may also transmit control information (e.g., assignmentsof system resources) to the UE. Similarly, the UE may transmit controlinformation to the Node B to support data transmission on the downlinkand/or for other purposes. It is desirable to send data and controlinformation as efficiently as possible in order to improve systemperformance.

SUMMARY

Techniques for sending data and control information in a wirelesscommunication system are described herein. Control information maycomprise acknowledgement (ACK) information, channel quality indicator(CQI) information, and/or other information. A UE may send only controlinformation, or only data, or both control information and data in agiven time interval.

In an aspect, control information may be sent in a first frequencylocation if data is not being sent and in a second frequency location ifdata is being sent. The first frequency location may correspond to afirst set of subcarriers assigned to the UE for sending controlinformation and may be associated with an assignment of subcarriers fordownlink transmission. The second frequency location may correspond to asecond set of subcarriers assigned to the UE for sending data when thereis data to send. The first and second sets may each include contiguoussubcarriers, which may improve peak-to-average ratio (PAR) of asingle-carrier frequency division multiplexing (SC-FDM) waveformcarrying control information and/or data.

In another aspect, control information may be processed in accordancewith a first processing scheme if data is not being sent and inaccordance with a second processing scheme if data is being sent. Forboth schemes, control information may be processed (e.g., encoded andsymbol mapped) to obtain modulation symbols. In one design of the firstprocessing scheme, a CAZAC (constant amplitude zero auto-correlation)sequence may be modulated with each of the modulation symbols to obtaina corresponding modulated CAZAC sequence, which may then be mapped tothe first set of subcarriers. In one design of the second processingscheme, the modulation symbols for control information may be combinedwith modulation symbols for data, e.g., by multiplexing these modulationsymbols or by puncturing some of the modulation symbols for data. Thecombined modulation symbols may be transformed from the time domain tothe frequency domain and then mapped to the second set of subcarriers.For both schemes, SC-FDM symbols may be generated based on the symbolsmapped to the first or second set of subcarriers.

The modulation symbols for control information may be generated based ona first modulation scheme (e.g., a fixed modulation scheme such as QPSK)if data is not being sent. These modulation symbols may be generatedbased on a second modulation scheme (e.g., a modulation scheme used fordata) if data is being sent. Control information may also be encodedbased on a first coding scheme if data is not being sent and based on asecond coding scheme if data is being sent.

Various aspects and features of the disclosure are described in furtherdetail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a wireless communication system.

FIG. 2 shows downlink transmission by a Node B and uplink transmissionby a UE.

FIG. 3 shows a structure for transmitting data and control information.

FIG. 4A shows transmission of control information on the uplink.

FIG. 4B shows transmission of control information and data on theuplink.

FIG. 5A shows transmission of control information with frequencyhopping.

FIG. 5B shows transmission of control information and data withfrequency hopping.

FIG. 6 shows a block diagram of a Node B and a UE.

FIG. 7 shows a block diagram of a modulator for control information.

FIG. 8 shows a block diagram of a modulated CAZAC sequence unit.

FIG. 9 shows a block diagram of a modulator for data.

FIG. 10 shows a block diagram of a modulator for control information anddata.

FIG. 11 shows a block diagram of a demodulator.

FIGS. 12 and 13 show a process and an apparatus, respectively, forsending control information in different frequency locations.

FIGS. 14 and 15 show a process and an apparatus, respectively, forreceiving control information from different frequency locations.

FIGS. 16 and 19 show a process and an apparatus, respectively, forsending control information with different processing schemes.

FIGS. 17 and 20 show a process and an apparatus, respectively, forsending control information based on a first processing scheme when nodata is being sent.

FIGS. 18 and 21 show a process and an apparatus, respectively, forsending control information based on a second processing scheme whendata is being sent.

FIGS. 22 and 23 show a process and an apparatus, respectively, forreceiving control information with different processing schemes.

FIGS. 24 and 25 show a process and an apparatus, respectively, forsending control information.

DETAILED DESCRIPTION

FIG. 1 shows a wireless communication system 100 with multiple Node Bs110 and multiple UEs 120. A Node B is generally a fixed station thatcommunicates with the UEs and may also be referred to as an evolved NodeB (eNode B), a base station, an access point, etc. Each Node B 110provides communication coverage for a particular geographic area andsupports communication for the UEs located within the coverage area. Theterm “cell” can refer to a Node B and/or its coverage area depending onthe context in which the term is used. A system controller 130 maycouple to the Node Bs and provide coordination and control for theseNode Bs. System controller 130 may be a single network entity or acollection of network entities, e.g., an Access Gateway (AGW), a RadioNetwork Controller (RNC), etc.

UEs 120 may be dispersed throughout the system, and each UE may bestationary or mobile. A UE may also be referred to as a mobile station,a mobile equipment, a terminal, an access terminal, a subscriber unit, astation, etc. A UE may be a cellular phone, a personal digital assistant(PDA), a wireless communication device, a handheld device, a wirelessmodem, a laptop computer, etc.

A Node B may transmit data to one or more UEs on the downlink and/orreceive data from one or more UEs on the uplink at any given moment. TheNode B may also transmit control information to the UEs and/or receivecontrol information from the UEs. In FIG. 1, a solid line with doublearrows (e.g., between Node B 110 a and UE 120 b) represents datatransmission on the downlink and uplink, and transmission of controlinformation on the uplink. A solid line with a single arrow pointing toa UE (e.g., UE 120 e) represents data transmission on the downlink, andtransmission of control information on the uplink. A solid line with asingle arrow pointing from a UE (e.g., UE 120 c) represents transmissionof data and control information on the uplink. A dashed line with asingle arrow pointing from a UE (e.g., UE 110 a) represents transmissionof control information (but no data) on the uplink. Transmission ofcontrol information on the downlink is not shown in FIG. 1 forsimplicity. A given UE may receive data on the downlink, transmit dataon the uplink, and/or transmit control information on the uplink at anygiven moment.

FIG. 2 shows example downlink transmission by a Node B and uplinktransmission by a UE. The UE may periodically estimate the downlinkchannel quality for the Node B and may send CQI to the Node B. The NodeB may use the CQI to select a suitable rate (e.g., a code rate and amodulation scheme) to use for downlink data transmission to the UE. TheNode B may process and transmit data to the UE whenever there is data tosend and system resources are available. The UE may process a downlinkdata transmission from the Node B and may send an acknowledgement (ACK)if the data is decoded correctly or a negative acknowledgement (NAK) ifthe data is decoded in error. The Node B may retransmit the data if aNAK is received and may transmit new data if an ACK is received. The UEmay also transmit data on the uplink to the Node B whenever there isdata to send and the UE is assigned uplink resources.

As shown in FIG. 2, the UE may transmit data and/or control information,or neither, in any given time interval. The control information may alsobe referred to as control, overhead, signaling, etc. The controlinformation may comprise ACK/NAK, CQI, other information, or anycombination thereof. The type and amount of control information may bedependent on various factors such as the number of data streams beingsent, whether multiple-input multiple-output (MIMO) is used fortransmission, etc. For simplicity, much of the following descriptionassumes that control information comprises ACK and CQI information. Inthe example shown in FIG. 2, the UE transmits data and controlinformation in time intervals n and n+6, only control information intime intervals n+3 and n+12, only data in time interval n+9, and no dataor control information in the remaining time intervals in FIG. 2. The UEmay efficiently transmit data and/or control information as describedbelow.

In general, the transmission techniques described herein may be used foruplink transmission as well as downlink transmission. The techniques mayalso be used for various wireless communication systems such as CDMA,TDMA, FDMA, OFDMA, and SC-FDMA systems. The terms “system” and “network”are often used interchangeably. A CDMA system may implement a radiotechnology such as Universal Terrestrial Radio Access (UTRA), cdma2000,etc. UTRA includes Wideband CDMA (W-CDMA) and Low Chip Rate (LCR).cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA system mayimplement a radio technology such as Global System for MobileCommunications (GSM). An OFDMA system may implement a radio technologysuch as Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20,Flash-OFDM®, etc. These various radio technologies and standards areknown in the art. UTRA, E-UTRA, and GSM are part of Universal MobileTelecommunication System (UMTS). Long Term Evolution (LTE) is anupcoming release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS andLTE are described in documents from an organization named “3rdGeneration Partnership Project” (3GPP). cdma2000 is described indocuments from an organization named “3rd Generation Partnership Project2” (3GPP2). For clarity, certain aspects of the techniques are describedbelow for uplink transmission in LTE, and 3GPP terminology is used inmuch of the description below.

LTE utilizes orthogonal frequency division multiplexing (OFDM) on thedownlink and single-carrier frequency division multiplexing (SC-FDM) onthe uplink. OFDM and SC-FDM partition the system bandwidth into multiple(N) orthogonal subcarriers, which are also commonly referred to astones, bins, etc. Each subcarrier may be modulated with data. Ingeneral, modulation symbols are sent in the frequency domain with OFDMand in the time domain with SC-FDM. For LTE, the spacing betweenadjacent subcarriers may be fixed, and the total number of subcarriers(N) may be dependent on the system bandwidth. In one design, N=512 for asystem bandwidth of 5 MHz, N=1024 for a system bandwidth of 10 MHz, andN=2048 for a system bandwidth of 20 MHz. In general, N may be anyinteger value.

FIG. 3 shows a design of a structure 300 that may be used for sendingdata and control information. The transmission time line may bepartitioned into slots. A slot may have a fixed duration, e.g., 0.5milliseconds (ms), or a configurable duration and may also be referredto as a transmission time interval (TTI), etc. In the design shown inFIG. 3, a slot includes eight symbol periods—six long symbol periodsused for data and control information and two short symbol periods usedfor pilot. Each short symbol period may be half the duration of a longsymbol period. A short symbol period may correspond to a short block(SB), and a long symbol period may correspond to a long block (LB). Inanother design, a slot includes seven symbol periods of equalduration—six symbol periods used for data and control information andone symbol period (e.g., in the middle of the slot) used for pilot. Ingeneral, a slot may include any number of symbol periods, which may haveequal or different durations. Each symbol period may be used for data,control information, pilot, or any combination thereof.

In the design shown in FIG. 3, the N total subcarriers may be dividedinto a data section and a control section. The control section may beformed at the lower edge of the system bandwidth, as shown in FIG. 3.Alternatively or additionally, a control section may be formed at theupper edge of the system bandwidth. A control section may have aconfigurable size, which may be selected based on the amount of controlinformation being sent on the uplink by the UEs. The data section mayinclude all subcarriers not included in the control section(s). Thedesign in FIG. 3 results in the data section including contiguoussubcarriers, which allows a single UE to be assigned all of thecontiguous subcarriers in the data section.

A UE may be assigned a control segment of M contiguous subcarriers,where M may be a fixed or configurable value. A control segment may alsobe referred to as a physical uplink control channel (PUCCH). In onedesign, a control segment includes an integer multiple of 12subcarriers. There may be a mapping between subcarriers assigned to theUE for downlink data transmission and subcarriers in the control segmentfor the UE. The UE would then know which subcarriers to use for itscontrol segment based on the assigned subcarriers for the downlink. TheUE may also be assigned a data segment of Q contiguous subcarriers,where Q may be a fixed or configurable value. A data segment may also bereferred to as a physical uplink shared channel (PUSCH). In one design,a data segment includes an integer multiple of 12 subcarriers. The UEmay also be assigned no data segment or no control segment in a givenslot.

It may be desirable for a UE to transmit on contiguous subcarriers usingSC-FDM, which is referred to as localized frequency divisionmultiplexing (LFDM). Transmitting on contiguous subcarriers (instead ofnon-contiguous subcarriers) may result in a lower peak-to-average ratio(PAR). PAR is the ratio of the peak power of a waveform to the averagepower of the waveform. A low PAR is desirable since it may allow a poweramplifier (PA) to be operated at an average output power closer to thepeak output power. This, in turn, may improve throughput and/or linkmargin for the UE.

The UE may be assigned a control segment located near an edge of thesystem bandwidth. The UE may also be assigned a data segment within thedata section. The subcarriers for the control segment may not beadjacent to the subcarriers for the data segment. The UE may send datain the data segment and may send control information in the controlsegment. In this case, the data and control information may be sent onnon-contiguous subcarriers in different parts of the system bandwidth,and the resulting waveform may have higher PAR.

In an aspect, the UE may send control information in different frequencylocations depending on whether or not there is data to send. The UE maysend control information in an assigned control segment if there is nodata to send on the uplink. The UE may send control information and datain an assigned data segment if there is data to send on the uplink. Thisdynamic transmission of control information allows the UE to transmit oncontiguous subcarriers regardless of whether or not data is being sent.

FIG. 4A shows transmission of control information when there is no datato send on the uplink. In this case, the UE may send control informationon an assigned control segment in each symbol period not used for pilot,or non-pilot symbol period. The UE may also transmit pilot in eachsymbol period used for pilot, or pilot symbol period. In each non-pilotsymbol period, the transmission from the UE may occupy a set ofcontiguous subcarriers in the assigned control segment. The remainingsubcarriers may be used by other UEs for uplink transmission.

FIG. 4B shows transmission of control information when there is data tosend on the uplink. In this case, the UE may send control informationand data on an assigned data segment in each non-pilot symbol period.The UE may process control information and generate modulation symbols.The UE may also process data and generate modulation symbols. The UE maymultiplex the modulation symbols for control information with themodulation symbols for data. Alternatively, the UE may puncture (orreplace) some of the modulation symbols for data with the modulationsymbols for control information. The UE may also send controlinformation and data in other manners. The UE may also transmit pilot ineach pilot symbol period. In each non-pilot symbol period, thetransmission from the UE may occupy a set of contiguous subcarriers inthe assigned data segment. The remaining subcarriers, if any, may beused by other UEs for uplink transmission.

The system may use frequency hopping to provide frequency diversityagainst deleterious path effects and randomization of interference. Withfrequency hopping, the UE may be assigned different sets of subcarriersin different hop periods. A hop period is an amount of time spent on agiven set of subcarriers and may correspond to one slot or some otherduration. Different sets of subcarriers may be selected based on ahopping pattern that may be known by the UE.

FIG. 5A shows transmission of control information with frequency hoppingwhen there is no data to send on the uplink. In this design, the UE maybe assigned a different set of subcarriers for the control segment ineach slot. The UE may send control information on the subcarriers forthe control segment in each non-pilot symbol period. The UE may transmitpilot in each pilot symbol period. In each non-pilot symbol period, thetransmission from the UE may occupy a set of contiguous subcarriersassigned to the UE. The remaining subcarriers may be used by other UEsfor uplink transmission.

FIG. 5B shows transmission of control information and data withfrequency hopping. In this design, the UE may be assigned a differentset of subcarriers for the data segment in each slot. The UE may sendcontrol information and data on the subcarriers for the data segment ineach non-pilot symbol period. The UE may transmit pilot in each pilotsymbol period. In each non-pilot symbol period, the transmission fromthe UE may occupy a set of contiguous subcarriers assigned to the UE.The remaining subcarriers, if any, may be used by other UEs for uplinktransmission.

FIGS. 5A and 5B show frequency hopping from slot to slot, with each hopperiod corresponding to one slot. Frequency hopping may also beperformed over other hop periods or time intervals. For example,frequency hopping may also be performed from subframe to subframe (whereone subframe may be equal to two slots), from symbol period to symbolperiod, etc.

FIGS. 3 through 5B show an example structure for sending controlinformation and data. Other structures may also be used to send controlinformation and data. In general, control information and data may besent using frequency division multiplexing (FDM), time divisionmultiplexing (TDM), and/or other multiplexing schemes.

FIG. 6 shows a block diagram of a design of a Node B 110 and a UE 120,which are one of the Node Bs and one of the UEs in FIG. 1. At UE 120, atransmit (TX) data and control processor 610 may receive uplink (UL)data from a data source (not shown) and/or control information from acontroller/processor 640. Processor 610 may process (e.g., format,encode, interleave, and symbol map) the data and control information andprovide modulation symbols. A modulator (MOD) 620 may process themodulation symbols as described below and provide output chips. Atransmitter (TMTR) 622 may process (e.g., convert to analog, amplify,filter, and frequency upconvert) the output chips and generate an uplinksignal, which may be transmitted via an antenna 624.

At Node B 120, an antenna 652 may receive the uplink signals from UE 120and other UEs and provide a received signal to a receiver (RCVR) 654.Receiver 654 may condition (e.g., filter, amplify, frequencydownconvert, and digitize) the received signal and provide receivedsamples. A demodulator (DEMOD) 660 may process the received samples asdescribed below and provide demodulated symbols. A receive (RX) data andcontrol processor 670 may process (e.g., symbol demap, deinterleave, anddecode) the demodulated symbols to obtain decoded data and controlinformation for UE 120 and other UEs.

On the downlink, at Node B 120, downlink (DL) data and controlinformation to be sent to the UEs may be processed by a TX data andcontrol processor 690, modulated by a modulator 692 (e.g., for OFDM),conditioned by a transmitter 694, and transmitted via antenna 652. At UE120, the downlink signals from Node B 110 and possibly other Node Bs maybe received by antenna 624, conditioned by a receiver 630, demodulatedby a demodulator 632 (e.g., for OFDM), and processed by an RX data andcontrol processor 634 to recover the downlink data and controlinformation sent by Node B 110 to UE 120. In general, the processing foruplink transmission may be similar to or different from the processingfor downlink transmission.

Controllers/processors 640 and 680 may direct the operations at UE 120and Node B 110, respectively. Memories 642 and 682 may store data andprogram codes for UE 120 and Node B 110, respectively. A scheduler 684may schedule UEs for downlink and/or uplink transmission and may provideassignments of system resources e.g., assignments of subcarriers fordownlink and/or uplink.

FIG. 7 shows a block diagram of a design of a modulator 620 a forcontrol information. Modulator 620 a may be used for modulator 620 at UE120 in FIG. 6. A TX control processor 710, which may be part of TX dataand control processor 610 in FIG. 6, may receive ACK and/or CQIinformation to be sent in a subframe, which may be two slots or someother duration. TX control processor 710 may process ACK information togenerate one or more modulation symbols for ACK. In one design, TXcontrol processor 710 may map an ACK/NAK to a QPSK modulation symbol,e.g., map an ACK to one QPSK value (e.g., 1+j) and a NAK to another QPSKvalue (e.g., −1−j). Alternatively or additionally, TX control processor710 may process CQI information to generate modulation symbols for CQI.In one design, TX control processor 710 may encode the CQI informationbased on a block code to obtain code bits and may then map the code bitsto QPSK modulation symbols. In general, TX control processor 710 mayprocess the ACK and CQI information either separately or jointly. Thenumber of modulation symbols to generate for the ACK and/or CQIinformation may be dependent on the modulation scheme/order used for ACKand CQI, the block code rate, the number of symbol periods available fortransmitting the ACK and CQI information, etc. TX control processor 710may provide modulation symbols for the ACK and/or CQI information.

Within modulator 620 a, a unit 722 may receive the modulation symbolsfor the ACK and/or CQI information from TX control processor 710, e.g.,one modulation symbol for each non-pilot symbol period. In eachnon-pilot symbol period, unit 722 may modulate a CAZAC sequence oflength M with the modulation symbol for that symbol period and provide amodulated CAZAC sequence with M modulated symbols, where M is the numberof subcarriers in the control segment assigned to UE 120. The processingby unit 722 is described below.

A spectral shaping unit 730 may receive the M modulated symbols fromunit 722, perform spectral shaping on these symbols in the frequencydomain based on a window size, and provide M spectrally shaped symbols.The spectral shaping may attenuate or roll off the symbols in the highand low subcarriers of the control segment in order to reducetime-domain transient in an output waveform. The spectral shaping may bebased on a raised cosine window or some other window function. Thewindow size may indicate the number of subcarriers to be used fortransmission. A symbol-to-subcarrier mapping unit 732 may map the Mspectrally shaped symbols to the M subcarriers in the control segmentassigned to UE 120 and may map zero symbols with signal value of zero tothe N-M remaining subcarriers.

An inverse discrete Fourier transform (IDFT) unit 734 may receive Nmapped symbols for the N total subcarriers from mapping unit 732,perform an N-point IDFT on these N symbols to transform the symbols fromthe frequency domain to the time domain, and provide N time-domainoutput chips. Each output chip is a complex value to be transmitted inone chip period. A parallel-to-serial converter (P/S) 736 may serializethe N output chips and provide a useful portion of an SC-FDM symbol. Acyclic prefix generator 738 may copy the last C output chips of theuseful portion and append these C output chips to the front of theuseful portion to form an SC-FDM symbol containing N+C output chips. Thecyclic prefix is used to combat inter-symbol interference (ISI) causedby frequency selective fading. The SC-FDM symbol may be sent in oneSC-FDM symbol period, which may be equal to N+C chip periods.

A CAZAC sequence is a sequence having good temporal characteristics(e.g., a constant time-domain envelope) and good spectralcharacteristics (e.g., a flat frequency spectrum). Some example CAZACsequences include a Chu sequence, a Zadoff-Chu sequence, a Franksequence, a generalized chirp-like (GCL) sequence, a Golomb sequence,P1, P3, P4 and Px sequences, etc., which are known in the art. In onedesign, a Chu sequence is used to send control information. A Chusequence of length M may be expressed as:C_(m)=e^(jφ) ^(m) , for m=1, . . . , M, Eq  (1)where φ_(m) is the phase of the m-th symbol or value in the Chusequence, and

C_(m) is the m-th symbol in the Chu sequence.

The phase φ_(m) for the Chu sequence may be expressed as:

$\begin{matrix}{\varphi_{m} = \left\{ \begin{matrix}{\pi \cdot \left( {m - 1} \right)^{2} \cdot {F/M}} & {{{for}\mspace{14mu} M\mspace{14mu}{even}},} \\{\pi \cdot \left( {m - 1} \right) \cdot m \cdot {F/M}} & {{{for}\mspace{14mu} M\mspace{14mu}{odd}},}\end{matrix} \right.} & {{Eq}\mspace{11mu}(2)}\end{matrix}$where F and M are relatively prime.

FIG. 8 shows a design of modulated CAZAC sequence unit 722 in FIG. 7.Within unit 722, M multipliers 812 a through 812 m may receive the Msymbols C₁ through C_(M), respectively, in the Chu sequence. Eachmultiplier 812 may also receive a modulation symbol S(i) to be sent inone symbol period, multiply its Chu symbol C_(m) with the modulationsymbol S(i), and provide a modulated symbol S_(m)(i), where mε{1, . . ., M}. M multipliers 812 a through 812 m may provide M modulated symbolsS₁(i) through S_(M)(i), respectively, for modulation symbol S(i).

Modulating the Chu sequence (or some other CAZAC sequence) with amodulation symbol does not destroy the good temporal and spectralcharacteristics of the Chu sequence. A waveform generated with amodulated Chu sequence may have lower PAR than a waveform generated byrepeating the modulation symbol M times. This may allow the waveform forthe modulated Chu sequence to be transmitted at higher power, which mayimprove reliability for the modulation symbol sent in the modulated Chusequence. A pseudo-CAZAC sequence with a small non-zero autocorrelationand small variations in amplitude may also be used instead of a trueCAZAC sequence with zero autocorrelation and no variations in amplitude.

Referring back to FIG. 7, for each subframe in which control informationis sent, TX control processor 710 may provide L modulation symbols forcontrol information, e.g., one modulation symbol in each non-pilotsymbol period of the subframe. L may be equal to the number of non-pilotsymbol periods in a subframe and may be equal to 12 for the design shownin FIG. 3. Each modulation symbol may modulate the Chu sequence as shownin FIG. 8, and the modulated Chu sequence may be sent on M contiguoussubcarriers of the control segment in one symbol period. If only ACKinformation is sent, then TX control processor 710 may generate amodulation symbol for the ACK information, repeat this modulation symbolto obtain L modulation symbols, and provide one modulation symbol ineach non-pilot symbol period. If only CQI information is sent, then TXcontrol processor 710 may encode the CQI information based on a blockcode to obtain code bits, map the code bits to L modulation symbols, andprovide one modulation symbol for CQI in each non-pilot symbol period.If both ACK and CQI information is sent, then TX control processor 710may encode the ACK and CQI information jointly based on another blockcode to obtain code bits, map the code bits to L modulation symbols, andprovide one modulation symbol in each non-pilot symbol period. TXcontrol processor 710 may also process the ACK and/or CQI information inother manners. The number of modulation symbols to provide for thecontrol information may be dependent on the number of non-pilot symbolsin a subframe. The number of code bits (and hence the block code) may bedependent on the number of modulation symbols, the modulation scheme,and the number of bits for the control information. In any case, themodulation symbols may be sent at a proper transmit power level, whichmay be dependent on whether ACK and/or CQI information is being sent.

FIG. 9 shows a block diagram of a design of a modulator 620 b for data.Modulator 620 b may also be used for modulator 620 in FIG. 6. A TX dataprocessor 712, which may be part of TX data and control processor 610 inFIG. 6, may receive data to send, encode the data based on a codingscheme to obtain code bits, interleave the code bits, and map theinterleaved bits to modulation symbols based on a modulation scheme,e.g., QPSK, 16-QAM, 64-QAM, etc. The code rate and modulation scheme maybe selected based on uplink channel conditions, which may be estimatedby Node B 110 and signaled to UE 120.

Within modulator 620 b, a serial-to-parallel converter (S/P) 724 mayreceive the modulation symbols from TX data processor 712 and provide Qmodulation symbols in each non-pilot symbol period, where Q is thenumber of subcarriers in the data segment assigned to UE 10. A discreteFourier transform (DFT) unit 728 may perform a Q-point DFT on the Qmodulation symbols to transform these symbols from the time domain tothe frequency domain and may provide Q frequency-domain symbols.Spectral shaping unit 730 may perform spectral shaping on the Qfrequency-domain symbols and provide Q spectrally shaped symbols.Symbol-to-subcarrier mapping unit 732 may map the Q spectrally shapedsymbols to the Q subcarriers in the data segment and may map zerosymbols to the N-Q remaining subcarriers. IDFT unit 734 may perform anN-point IDFT on the N mapped symbols from unit 732 and provide Ntime-domain output chips. P/S 736 may serialize the N output chips, andcyclic prefix generator 738 may append a cyclic prefix to form an SC-FDMsymbol containing N+C output chips.

FIG. 10 shows a block diagram of a design of a modulator 620 c for dataand control information. Modulator 620 c may also be used for modulator620 in FIG. 6. TX control processor 710 may process control informationand provide modulation symbols for control information to modulator 620c. TX data processor 712 may process data and provide modulation symbolsfor data to modulator 620 c.

Within modulator 620 c, an S/P 726 may receive the modulation symbolsfrom TX control processor 710 and the modulation symbols from TX dataprocessor 712. S/P 726 may provide Q modulation symbols in eachnon-pilot symbol period, where Q is the number of subcarriers in thedata segment assigned to UE 10. The Q modulation symbols may beprocessed by DFT unit 728, spectral shaping unit 730,symbol-to-subcarrier mapping unit 732, IDFT unit 734, S/P 736, andcyclic prefix generator 738 as described above for FIG. 9 to generate anSC-FDM symbol containing N+C output chips.

Control information may be processed and sent with data in the datasegment in various manners. Some designs for processing and sendingcontrol information with data are described below.

In one design, TX control processor 710 may generate modulation symbolsfor control information in the same manner (e.g., based on apredetermined coding and modulation scheme) regardless of whethercontrol information is sent alone or with data. If control informationis sent alone then TX control processor 710 may provide the modulationsymbols for control information to modulator 620 a in FIG. 7. If controlinformation is sent with data, then TX control processor 710 may furtherprocess the modulation symbols. In one design, TX control processor 710may repeat a modulation symbol for control information (e.g., ACK) asufficient number of times to achieve the desired reliability. Inanother design, TX control processor 710 may spread a modulation symbolfor control information with an orthogonal code of length W to generateW spread modulation symbols, where W may be equal to or less than M. TXcontrol processor 710 may perform repetition for one type of controlinformation, spreading for another type of control information, and/orother processing for other types of control information. In any case, TXcontrol processor 710 may provide all of the repeated and/or spreadmodulation symbols for control information to modulator 620 c.

In another design, TX control processor 710 may generate modulationsymbols for control information (i) based on a predetermined modulationscheme (e.g., QPSK) when data is not sent or (ii) based on a modulationscheme (e.g., 16-QAM, 64-QAM, etc.) used for data when data is sent. Forexample, when control information is sent with data, the modulationscheme for CQI may change from QPSK to the modulation scheme used fordata, and the coding basis for ACK may change from the Chu sequence to arepetition code followed by a change from QPSK to the modulation schemeused for data. TX control processor 710 may use the same coding schemefor control information regardless of the modulation scheme used forcontrol information. Alternatively, TX control processor 710 may selecta coding scheme or a code rate based on the modulation scheme used forcontrol information.

In one design, TX data processor 712 may generate modulation symbols fordata in the same manner regardless of whether data is sent alone or withcontrol information. S/P 726 may puncture (or replace) some of themodulation symbols for data with the modulation symbols for controlinformation when control information is sent with data. In anotherdesign, TX data processor 712 may generate fewer modulation symbols fordata (e.g., by adjusting the code rate) when control information is sentwith data. S/P 726 may multiplex the modulation symbols for controlinformation with the modulation symbols for data. The modulation symbolsfor control information may also be sent with the modulation symbols fordata in other manners, e.g., with superposition using hierarchicalcoding.

In the design shown in FIG. 10, the modulation symbols for controlinformation may puncture or may be multiplexed with the modulationsymbols for data, prior to the DFT by unit 726. This design ensures thatan SC-FDM waveform, which may be generated by a DFT operation followedby an IDFT operation when only data or both data and control informationare sent, is preserved. In another design, the modulation symbols forcontrol information may puncture or may be multiplexed with themodulation symbols for data after the DFT, e.g., prior to mapping unit732.

As shown in FIGS. 7 and 10, control information may be sent usingdifferent processing schemes depending on whether control information issent alone or with data. When sent alone, control information may besent using a CAZAC sequence to achieve a lower PAR. The lower PAR mayallow for use of higher transmit power, which may improve link margin.When sent with data, control information may be multiplexed with dataand processed in similar manner as data. This may allow controlinformation to be recovered using the same techniques used for data,e.g., coherent demodulation based on pilot symbols sent with themodulation symbols. Control information may also be sent in othermanners. For example, control information may be sent using codedivision multiplexing (CDM), e.g., by spreading each modulation symbolfor control information with an orthogonal code and mapping the spreadmodulation symbols to subcarriers used for control information.

FIG. 11 shows a block diagram of a design of demodulator 660 at Node B110 in FIG. 6. Within demodulator 660, a cyclic prefix removal unit 1110may obtain N+C received samples in each SC-FDM symbol period, remove Creceived samples corresponding to the cyclic prefix, and provide Nreceived samples for the useful portion of a received SC-FDM symbol. AnS/P 1112 may provide the N received samples in parallel. A DFT unit 1114may perform an N-point DFT on the N received samples and provide Nreceived symbols for the N total subcarriers. These N received symbolsmay contain data and control information for all UEs transmitting toNode B 110. The processing to recover control information and/or datafrom UE 120 is described below.

If control information and data are sent by UE 120, then asymbol-to-subcarrier demapping unit 1116 may provide Q received symbolsfrom the Q subcarriers in the data segment assigned to UE 120 and maydiscard the remaining received symbols. A unit 1118 may scale the Qreceived symbols based on the spectral shaping performed by UE 120. Unit1118 may further perform data detection (e.g., matched filtering,equalization, etc.) on the Q scaled symbols with channel gain estimatesand provide Q detected symbols. An IDFT unit 1120 may perform a Q-pointIDFT on the Q detected symbols and provide Q demodulated symbols fordata and control information. A P/S 1122 may provide demodulated symbolsfor data to an RX data processor 1150 and may provide demodulatedsymbols for control information to a multiplexer (Mux) 1132, which mayprovide these symbols to an RX control processor 1152. Processors 1150and 1152 may be part of RX data and control processor 670 in FIG. 6. RXdata processor 1150 may process (e.g., symbol demap, deinterleave, anddecode) the demodulated symbols for data and provide decoded data. RXcontrol processor 1152 may process the demodulated symbols for controlinformation and provide decoded control information, e.g., ACK and/orCQI.

If control information and no data is sent by UE 120, thensymbol-to-subcarrier demapping unit 1116 may provide M received symbolsfrom the M subcarriers in the control segment assigned to UE 120 and maydiscard the remaining received symbols. A CAZAC sequence detector 1130may detect a modulation symbol most likely to have been sent in a symbolperiod based on the M received symbols for that symbol period. Detector1130 may provide demodulated symbols for control information, which maybe routed through multiplexer 1132 and provided to RX control processor1152.

If only data is sent by UE 120, then symbol-to-subcarrier demapping unit1116 may provide Q received symbols from the Q subcarriers in the datasegment and may discard the remaining received symbols. These Q receivedsymbols may be scaled and detected by unit 1118, transformed by IDFTunit 1120, and routed via P/S 1122 to RX data processor 1150.

FIG. 12 shows a design of a process 1200 for sending controlinformation. Process 1200 may be performed by a UE. An assignment ofsubcarriers for downlink transmission may be received (block 1212). Afirst frequency location to use for sending control information may bedetermined based on the assignment (block 1214). The first frequencylocation may also be assigned explicitly or determined in other manners.Control information may be sent in the first frequency location if datais not being sent (block 1216). Control information and data may be sentin a second frequency location that is different from the firstfrequency location if data is being sent (block 1218). The controlinformation may comprise ACK information, CQI information, and/or otherinformation.

The first frequency location may correspond to a first set ofsubcarriers assigned to the UE for sending control information. Thesecond frequency location may correspond to a second set of subcarriersassigned to the UE for sending data. Control information and/or data maybe sent on contiguous subcarriers in each symbol period in which controlinformation and/or data is sent. Control information may also be sent indifferent frequency locations in different time intervals with frequencyhopping, e.g., as shown in FIGS. 5A and 5B.

Control information may be processed to obtain modulation symbols. Datamay also be processed to obtain modulation symbols. The modulationsymbols for control information may be multiplexed with the modulationsymbols for data. Alternatively, some of the modulation symbols for datamay be punctured with the modulation symbols for control information.SC-FDM symbols may be generated with control information mapped to thefirst frequency location if data is not being sent. SC-FDM symbols maybe generated with control information and data mapped to the secondfrequency location if data is being sent.

FIG. 13 shows a design of an apparatus 1300 for sending controlinformation. Apparatus 1300 includes means for receiving an assignmentof subcarriers for downlink transmission (module 1312), means fordetermining a first frequency location to use for sending controlinformation based on the assignment (module 1314), means for sendingcontrol information in the first frequency location if data is not beingsent (module 1316), and means for sending control information and datain a second frequency location that is different from the firstfrequency location if data is being sent (module 1318).

FIG. 14 shows a design of a process 1400 for receiving controlinformation. Process 1400 may be performed by a Node B. An assignment ofsubcarriers for downlink transmission may be sent to a UE (block 1412).A first frequency location to be used by the UE for sending controlinformation may be determined based on the assignment (block 1414).Control information may be received from the UE in the first frequencylocation if data is not sent by the UE (block 1416). Control informationand data may be received from the UE in a second frequency location thatis different from the first frequency location if data is sent by the UE(block 1418).

Received SC-FDM symbols may be processed to obtain received symbols. Ifdata is not sent by the UE, then received symbol for control informationmay be obtained from the first frequency location, e.g., a first set ofcontiguous subcarriers. These received symbols may be detected andprocessed to obtain control information sent by the UE. If data is sentby the UE, then received symbols for control information and data may beobtained from the second frequency location, e.g., a second set ofcontiguous subcarriers. These received symbols may be converted fromfrequency domain to time domain and may then be demultiplexed to obtaindemodulated symbols for control information and demodulated symbols fordata, e.g., as shown in FIG. 11. The demodulated symbols for controlinformation may be processed to obtain control information sent by theUE. The demodulated symbols for data may be processed to obtain datasent by the UE.

FIG. 15 shows a design of an apparatus 1500 for receiving controlinformation. Apparatus 1500 includes means for sending an assignment ofsubcarriers for downlink transmission to a UE (module 1512), means fordetermining a first frequency location to be used by the UE for sendingcontrol information based on the assignment (module 1514), means forreceiving control information from the UE in the first frequencylocation if data is not sent by the UE (module 1516), and means forreceiving control information and data from the UE in a second frequencylocation that is different from the first frequency location if data issent by the UE (module 1518).

FIG. 16 shows a design of a process 1600 for sending controlinformation. Process 1600 may be performed by a UE. Control informationmay be processed in accordance with a first processing scheme if data isnot being sent (block 1610). Control information may be processed inaccordance with a second processing scheme if data is being sent (block1620). The control information may comprise ACK information, CQIinformation, etc.

FIG. 17 shows a design of the first processing scheme in block 1610.Control information may be processed to obtain modulation symbols (block1712). A CAZAC sequence (e.g., a Chu sequence) may be modulated witheach of the modulation symbols to obtain a corresponding modulated CAZACsequence (block 1714). Each modulated CAZAC sequence may be mapped to afirst set of subcarriers (block 1716). The first processing scheme mayalso perform processing in other manners.

FIG. 18 shows a design of the second processing scheme in block 1620.Control information may be processed to obtain modulation symbols (block1812). The modulation symbols for control information may be combinedwith modulation symbols for data (block 1814). The combining may beachieved by multiplexing the modulation symbols for control informationwith modulation symbols for data, by puncturing some of the modulationsymbols for data with the modulation symbols for control information,etc. The combined modulation symbols may be transformed from the timedomain to the frequency domain to obtain frequency-domain symbols (block1816). The frequency-domain symbols may be mapped to a second set ofsubcarriers (block 1818). The second processing scheme may also performprocessing in other manners.

In one design of the first processing scheme, an ACK may be mapped to amodulation symbol. A Chu sequence may be modulated with the modulationsymbol to obtain a modulated Chu sequence for the ACK. The modulated Chusequence may be mapped to the first set of subcarriers in one symbolperiod. In one design of the second processing scheme, the ACK may bemapped to a modulation symbol. The modulation symbol may be repeatedmultiple times to obtain repeated modulation symbols or may be spreadwith an orthogonal sequence to obtain spread modulation symbols. Therepeated or spread modulation symbols for the ACK may be combined withmodulation symbols for data. The combined modulation symbols may bemapped to the second set of subcarriers.

The modulation symbols for control information may be generated based ona first modulation scheme if data is not being sent and based on asecond modulation scheme if data is being sent. The first modulationscheme may be a fixed modulation scheme, e.g., QPSK. The secondmodulation scheme may be the modulation scheme used for data. Controlinformation may also be encoded based on a first coding scheme if datais not being sent and based on a second coding scheme if data is beingsent.

If data is not being sent by the UE, then frequency-domain symbols maybe obtained for control information and mapped to the first set ofcontiguous subcarriers used for control information. If data is beingsent by the UE, then frequency-domain symbols may be obtained forcontrol information and data and mapped to the second set of contiguoussubcarriers used for data. SC-FDM symbols may be generated based on themapped symbols.

FIG. 19 shows a design of an apparatus 1900 for sending controlinformation. Apparatus 1900 includes means for processing controlinformation in accordance with a first processing scheme if data is notbeing sent (module 1910) and means for processing control information inaccordance with a second processing scheme if data is being sent (module1920).

FIG. 20 shows a design of module 1910 in FIG. 19. Module 1910 includesmeans for processing control information to obtain modulation symbols(module 2012), means for modulating a CAZAC sequence with each of themodulation symbols to obtain a corresponding modulated CAZAC sequence(module 2014), and means for mapping each modulated CAZAC sequence to afirst set of subcarriers (module 2016).

FIG. 21 shows a design of module 1920 in FIG. 19. Module 1920 includesmeans for processing control information to obtain modulation symbols(module 2112), means for combining the modulation symbols for controlinformation with modulation symbols for data (module 2114), means fortransforming the combined modulation symbols from the time domain to thefrequency domain to obtain frequency-domain symbols (module 2116), andmeans for mapping the frequency-domain symbols to a second set ofsubcarriers (module 2118).

FIG. 22 shows a design of a process 2200 for receiving controlinformation. Process 2200 may be performed by a Node B. Received SC-FDMsymbols may be processed to obtain received symbols for N totalsubcarriers. Received symbols for a UE may be obtained from a first setof subcarriers if data is not sent by the UE or from a second set ofsubcarriers if data is sent by the UE (block 2212). The received symbolsfor the UE may be processed in accordance with a first processing schemeto obtain control information for the UE if data is not sent by the UE(block 2214). The received symbols for the UE may be processed inaccordance with a second processing scheme to obtain control informationfor the UE if data is sent by the UE (block 2216).

In one design of the first processing scheme, detection may be performedon the received symbols based on a CAZAC sequence to obtain demodulatedsymbols. The demodulated symbols may be processed to obtain controlinformation sent by the UE. In one design of the second processingscheme, data detection may be performed on the received symbols toobtain detected symbols. The detected symbols may be transformed fromthe frequency domain to the time domain to obtain demodulated symbols.The demodulated symbols may be further processed to obtain controlinformation sent by the UE. In general, the first and second processingschemes may be performed in a manner complementary to the processingperformed by the UE.

FIG. 23 shows a design of an apparatus 2300 for receiving controlinformation. Apparatus 2300 includes means for obtaining receivedsymbols for a UE from a first set of subcarriers if data is not sent bythe UE or from a second set of subcarriers if data is sent by the UE(module 2312), means for processing the received symbols for the UE inaccordance with a first processing scheme to obtain control informationfor the UE if data is not sent by the UE (module 2314), and means forprocessing the received symbols for the UE in accordance with a secondprocessing scheme to obtain control information for the UE if data issent by the UE (module 2316).

FIG. 24 shows a design of a process 2400 for sending controlinformation. Process 2400 may be performed by a UE. A frequency locationto use for sending control information may be determined based on anassignment for downlink transmission (block 2412). Control information(e.g., ACK information, CQI information, etc.) may be processed based ona CAZAC sequence (e.g., a Chu sequence) to obtain modulated symbols(block 2414). The modulated symbols may be sent in the frequencylocation determined based on the assignment (block 2416).

For example, an ACK may be mapped to a modulation symbol. The CAZACsequence may be modulated with the modulation symbol to obtain modulatedsymbols for a modulated CAZAC sequence. The modulated symbols may besent in a set of contiguous subcarriers in the frequency locationdetermined based on the assignment. The control information may be sentin different frequency locations in different time intervals withfrequency hopping.

FIG. 25 shows a design of an apparatus 2500 for sending controlinformation. Apparatus 2500 includes means for determining a frequencylocation to use for sending control information based on an assignmentfor downlink transmission (module 2512), means for processing controlinformation based on a CAZAC sequence to obtain modulated symbols(module 2514), and means for sending the modulated symbols in thefrequency location determined based on the assignment (module 2516).

For clarity, transmission of control information and data on the uplinkwith SC-FDM has been described. The techniques may also be used fortransmission of control information and data on the downlink. Thecontrol information and data may also be sent with OFDM or some othermodulation techniques with multiple subcarriers.

The modules in FIGS. 13, 15, 19, 20, 21, 23 and 25 may compriseprocessors, electronics devices, hardware devices, electronicscomponents, logical circuits, memories, etc., or any combinationthereof.

The techniques described herein may be implemented by various means. Forexample, these techniques may be implemented in hardware, firmware,software, or a combination thereof. For a hardware implementation, theprocessing units used to perform the techniques at an entity (e.g., a UEor a Node B) may be implemented within one or more application specificintegrated circuits (ASICs), digital signal processors (DSPs), digitalsignal processing devices (DSPDs), programmable logic devices (PLDs),field programmable gate arrays (FPGAs), processors, controllers,micro-controllers, microprocessors, electronic devices, other electronicunits designed to perform the functions described herein, a computer, ora combination thereof.

For a firmware and/or software implementation, the techniques may beimplemented with modules (e.g., procedures, functions, etc.) thatperform the functions described herein. The firmware and/or softwareinstructions may be stored in a memory (e.g., memory 642 or 682 in FIG.6) and executed by a processor (e.g., processor 640 or 680). The memorymay be implemented within the processor or external to the processor.The firmware and/or software instructions may also be stored in otherprocessor-readable medium such as random access memory (RAM), read-onlymemory (ROM), non-volatile random access memory (NVRAM), programmableread-only memory (PROM), electrically erasable PROM (EEPROM), FLASHmemory, compact disc (CD), magnetic or optical data storage device, etc.

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe examples and designs described herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

1. An apparatus for wireless communication, comprising: at least oneprocessor configured to determine a time interval in which to sendcontrol information, to determine whether data is being sent in the timeinterval, to send only the control information in the time interval at afirst frequency location within a first frequency range if the data isnot being sent in the time interval, and to send both the controlinformation and the data in the time interval at a second frequencylocation within a second frequency range if the data is being sent inthe time interval, the first frequency range being non-overlapping withthe second frequency range; and a memory coupled to the at least oneprocessor.
 2. The apparatus of claim 1, wherein the at least oneprocessor is configured to receive an assignment of subcarriers fordownlink transmission, and to determine the first frequency locationbased on the assignment.
 3. The apparatus of claim 1, wherein the firstfrequency location corresponds to a first set of subcarriers assignedfor sending the control information, and wherein the second frequencylocation corresponds to a second set of subcarriers assigned for sendingthe data.
 4. The apparatus of claim 1, wherein the at least oneprocessor is configured to send only the control information, or onlythe data, or both the control information and the data on contiguoussubcarriers in each symbol period in which the control information, orthe data, or both are sent.
 5. The apparatus of claim 1, wherein if thedata is not being sent in the time interval the at least one processoris configured to generate symbols for only the control information andto map the symbols for only the control information to a first set ofsubcarriers corresponding to the first frequency location.
 6. Theapparatus of claim 5, wherein if the data is being sent in the timeinterval the at least one processor is configured to generate symbolsfor both the control information and the data and to map the symbols forboth the control information and the data to a second set of subcarrierscorresponding to the second frequency location.
 7. The apparatus ofclaim 1, wherein the at least one processor is configured to generatesingle-carrier frequency division multiplexing (SC-FDM) symbols withonly the control information mapped to the first frequency location ifthe data is not being sent in the time interval, and to generate SC-FDMsymbols with both the control information and the data mapped to thesecond frequency location if the data is being sent in the timeinterval.
 8. The apparatus of claim 1, wherein the at least oneprocessor is configured to send only the control information atdifferent frequency locations in different time intervals with frequencyhopping.
 9. The apparatus of claim 1, wherein the control informationcomprises acknowledgement (ACK) information, or channel qualityindicator (CQI) information, or both.
 10. A method of wirelesscommunication, comprising: determining a time interval in which to sendcontrol information; determining whether data is being sent in the timeinterval; sending only the control information in the time interval at afirst frequency location within a first frequency range if the data isnot being sent in the time interval; and sending both the controlinformation and the data in the time interval at a second frequencylocation within a second frequency range if the data is being sent inthe time interval, the first frequency range being non-overlapping withthe second frequency range.
 11. The method of claim 10, furthercomprising: receiving an assignment of subcarriers for downlinktransmission; and determining the first frequency location based on theassignment.
 12. The method of claim 10, wherein the sending only thecontrol information in the first frequency location comprises generatingsymbols for only the control information, and mapping the symbols foronly the control information to a first set of subcarriers correspondingto the first frequency location.
 13. The method of claim 12, wherein thesending both the control information and the data in the secondfrequency location comprises generating symbols for both the controlinformation and the data, and mapping the symbols for both the controlinformation and the data to a second set of subcarriers corresponding tothe second frequency location.
 14. An apparatus for wirelesscommunication, comprising: means for determining a time interval inwhich to send control information; means for determining whether data isbeing sent in the time interval; means for sending only the controlinformation in the time interval at a first frequency location within afirst frequency range if the data is not being sent in the timeinterval; and means for sending both the control information and thedata in the time interval at a second frequency location within a secondfrequency range if the data is being sent in the time interval, thefirst frequency range being non-overlapping with the second frequencyrange.
 15. The apparatus of claim 14, further comprising: means forreceiving an assignment of subcarriers for downlink transmission; andmeans for determining the first frequency location based on theassignment.
 16. The apparatus of claim 14, wherein the means for sendingonly the control information in the first frequency location comprisesmeans for generating symbols for only the control information, and meansfor mapping the symbols for only the control information to a first setof subcarriers corresponding to the first frequency location.
 17. Theapparatus of claim 16, wherein the means for sending both the controlinformation and the data in the second frequency location comprisesmeans for generating symbols for both the control information and thedata, and means for mapping the symbols for both the control informationand the data to a second set of subcarriers corresponding to the secondfrequency location.
 18. A non-transitory processor-readable mediumincluding instructions stored thereon, comprising: instructions fordetermining a time interval in which to send control information,instructions for determining whether data is being sent in the timeinterval; instructions for sending only the control information in thetime interval at a first frequency location within a first frequencyrange if the data is not being sent in the time interval; andinstructions for sending both the control information and the data inthe time interval at a second frequency location within a secondfrequency range if the data is being sent in the time interval, thefirst frequency range being non-overlapping with the second frequencyrange.
 19. The non-transitory processor-readable medium of claim 18,further comprising: instructions for receiving an assignment ofsubcarriers for downlink transmission; and instructions for determiningthe first frequency location based on the assignment.
 20. Thenon-transitory processor-readable medium of claim 18, wherein theinstructions for sending only the control information compriseinstructions for generating symbols for only the control information,and instructions for mapping the symbols for only the controlinformation to a first set of subcarriers corresponding to the firstfrequency location.
 21. The non-transitory processor-readable medium ofclaim 20, wherein the instructions for sending both the controlinformation and the data comprise instructions for generating symbolsfor both the control information and the data, and instructions formapping the symbols for both the control information and the data to asecond set of subcarriers corresponding to the second frequencylocation.
 22. An apparatus for wireless communication, comprising: atleast one processor configured to determine a time interval in which toreceive control information from a user equipment (UE), to determinewhether data is being sent by the UE in the time interval, to receiveonly the control information from the UE in the time interval at a firstfrequency location within a first frequency range if the data is notsent by the UE in the time interval, and to receive both the controlinformation and the data from the UE in the time interval at a secondfrequency location within a second frequency range if the data is sentby the UE in the time interval, the first frequency range beingnon-overlapping with the second frequency range; and a memory coupled tothe at least one processor.
 23. The apparatus of claim 22, wherein theat least one processor is configured to send an assignment ofsubcarriers for downlink transmission to the UE, and to determine thefirst frequency location based on the assignment.
 24. The apparatus ofclaim 22, wherein if the data is not sent by the UE in the time intervalthe at least one processor is configured to obtain received symbols froma first set of subcarriers corresponding to the first frequencylocation, and to obtain demodulated symbols for the control informationbased on the received symbols.
 25. The apparatus of claim 24, wherein ifthe data is sent by the UE in the time interval the at least oneprocessor is configured to obtain received symbols from a second set ofsubcarriers corresponding to the second frequency location, to obtaindemodulated symbols based on the received symbols, and to demultiplexthe demodulated symbols to obtain demodulated symbols for the controlinformation and demodulated symbols for the data.
 26. The apparatus ofclaim 22, wherein the at least one processor is configured to processreceived single-carrier frequency division multiplexing (SC-FDM) symbolsto obtain received symbols for only the control information from thefirst frequency location if the data is not sent by the UE in the timeinterval, and to process the received SC-FDM symbols to obtain receivedsymbols for both the control information and the data from the secondfrequency location if the data is sent by the UE in the time interval.27. A method of wireless communication, comprising: determining a timeinterval in which to receive control information from a user equipment(UE); determining whether data is being sent by the UE in the timeinterval; receiving only the control information from the UE in the timeinterval at a first frequency location within a first frequency range ifthe data is not sent by the UE in the time interval; and receiving boththe control information and the data from the UE in the time interval ata second frequency location within a second frequency range if the datais sent by the UE in the time interval, the first frequency range beingnon-overlapping with the second frequency range.
 28. The method of claim27, further comprising: sending an assignment of subcarriers fordownlink transmission to the UE; and determining the first frequencylocation based on the assignment.
 29. The method of claim 27, whereinthe receiving only the control information from the UE in the firstfrequency location comprises obtaining received symbols from a first setof subcarriers corresponding to the first frequency location, andobtaining demodulated symbols for the control information based on thereceived symbols.
 30. The method of claim 29, wherein the receiving boththe control information and the data from the UE in the second frequencylocation comprises obtaining received symbols from a second set ofsubcarriers corresponding to the second frequency location, obtainingdemodulated symbols based on the received symbols, and demultiplexingthe demodulated symbols to obtain demodulated symbols for the controlinformation and demodulated symbols for the data.
 31. The method ofclaim 10, wherein the control information comprises acknowledgement(ACK) information, or channel quality indicator (CQI) information, orboth.
 32. The method of claim 10, wherein the first frequency range isat an edge of system bandwidth and is designated for sending controlinformation, and wherein the second frequency range covers a middleportion of the system bandwidth and is usable for sending only data orboth data and control information.
 33. The method of claim 10, whereinthe first frequency location corresponds to a first set of subcarriersassigned for sending the control information, and wherein the secondfrequency location corresponds to a second set of subcarriers assignedfor sending the data.
 34. The method of claim 33, wherein the first setof subcarriers is for a Physical Uplink Control Channel (PUCCH), andwherein the second set of subcarriers is for a Physical Uplink SharedChannel (PUSCH).
 35. The method of claim 27, wherein the controlinformation comprises acknowledgement (ACK) information, or channelquality indicator (CQI) information, or both.
 36. The method of claim27, wherein the first frequency range is at an edge of system bandwidthand is designated for sending control information, and wherein thesecond frequency range covers a middle portion of the system bandwidthand is usable for sending only data or both data and controlinformation.
 37. The method of claim 27, wherein the first frequencylocation corresponds to a first set of subcarriers assigned for sendingthe control information, and wherein the second frequency locationcorresponds to a second set of subcarriers assigned for sending thedata.
 38. The method of claim 37, wherein the first set of subcarriersis for a Physical Uplink Control Channel (PUCCH), and wherein the secondset of subcarriers is for a Physical Uplink Shared Channel (PUSCH). 39.An apparatus for wireless communication, comprising: means fordetermining a time interval in which to receive control information froma user equipment (UE); means for determining whether data is being sentby the UE in the time interval; means for receiving only the controlinformation from the UE in the time interval at a first frequencylocation within a first frequency range if the data is not sent by theUE in the time interval; and means for receiving both the controlinformation and the data from the UE in the time interval at a secondfrequency location within a second frequency range if the data is sentby the UE in the time interval, the first frequency range beingnon-overlapping with the second frequency range.
 40. The apparatus ofclaim 39, further comprising: means for sending an assignment ofsubcarriers for downlink transmission to the UE; and means fordetermining the first frequency location based on the assignment. 41.The apparatus of claim 39, wherein the means for receiving only thecontrol information from the UE in the first frequency locationcomprises means for obtaining received symbols from a first set ofsubcarriers corresponding to the first frequency location, and means forobtaining demodulated symbols for the control information based on thereceived symbols.
 42. The apparatus of claim 41, wherein the means forreceiving both the control information and the data from the UE in thesecond frequency location comprises means for obtaining received symbolsfrom a second set of subcarriers corresponding to the second frequencylocation, means for obtaining demodulated symbols based on the receivedsymbols, and means for demultiplexing the demodulated symbols to obtaindemodulated symbols for the control information and demodulated symbolsfor the data.
 43. A non-transitory processor-readable medium includinginstructions stored thereon, comprising: instructions for determining atime interval in which to receive control information from a userequipment (UE); instructions for determining whether data is being sentby the UE in the time interval; instructions for receiving only thecontrol information from the UE in the time interval at a firstfrequency location within a first frequency range if the data is notsent by the UE in the time interval; and instructions for receiving boththe control information and the data from the UE in the time interval ata second frequency location within a second frequency range if the datais sent by the UE in the time interval, the first frequency range beingnon-overlapping with the second frequency range.